The use of frozen food in the home is ever increasing. It is well known that if power to the freezer should lapse or if the freezer door is accidentally left open, the food therein may thaw to a point where the food must immediately be used since it will spoil upon refreezing. Accordingly, it is quite important to be apprised as quickly as possible by a suitable signal of an abnormally high temperature in a freezer so that corrective action could be taken to save the food therein. Of particular importance is a lapse of power, which is of sufficient length to thaw the food, followed by a return of power. If one who has been away from home or sleeping during the power lapse, doesn't notice that an electrical clock has lost time, the food in the freezer will be refrozen and consequently ruined.
While various alarm devices for refrigeration systems are known in the prior art, these systems are apparently too expensive to be incorporated in a home freezer or refrigerator. Also none of the prior art refrigeration alarm systems of which we are aware provide an enduring indication of a thawing condition which indication persists after the condition corrects itself.